1. Field of the Invention
The present invention relates to prosthetic devices, and in one embodiment, relates to an insert for the socket of a prosthetic device incorporating multiple cells to compensate for volume fluctuations of a residual limb.
2. Description of the Related Art
With the ever-increasing number of amputees needing prosthetic devices, various types of prosthetic devices have been developed. In the past, prosthetic devices usually comprised some form of artificial limb or rod. More recently, other devices have been made to imitate the structure of the human limbs, as well as to simulate their natural movement. Many consisted of a hinge to allow movement at joints. These devices also include a socket for connecting the prosthetic device to the residual limb.
Most new amputations are either slightly bulbous or cylindrical in shape while older amputations that may have had a lot of atrophy are generally more conical in shape. Residual limbs may further be characterized by their various individual problems and configurations including the volume and shape of a residual limb and possible scar, skin graft, bony prominence, uneven limb volume, neuroma, pain, edema, or soft tissue configurations.
The volume of a residual limb changes significantly over the course of a day and throughout an amputee's lifetime. Consequently, sockets for receiving a residual limb may not always fit properly due to this volume variation. Moreover, particular activities may cause changes to the volume within a socket. The situation is analogous to how a ring worn on a finger may sometimes feel loose or tight at various times during the day.
Prior art attempts to compensate for this volume variation have included the use of silicone liners and inflatable bladders. Such devices however do not adequately address specific volume variations for an amputee's residual limb within a socket.
Attempts have also been made to improve the comfort of the socket by utilizing air cushions in various prosthetic devices, but none were designed to enhance activity levels beyond the expected sedentary levels of most amputees or compensate for volume fluctuations. Suction suspension sockets, wherein an elevated vacuum is provided between the liner and the socket wall, have also been designed to try to compensate for the volume fluctuations. A drawback to suction suspension arises from the fact that a standard socket, whether flexible or rigid, has a fixed, constant volume.
Another problem with air cushions is that such devices apply constant, unrelieved pressure. The situation is similar to that of bed sores, where the constant pressure can adversely affect blood supply. Moreover, because air is compressible, air cushions are too bouncy, which can cause portions of a residual limb to simply bounce off of the cushion, rather than providing effective volume control.
Some individuals fit socks over their residual limb in an attempt to make the prosthesis more comfortable. Several layers of socks may form a reasonably soft cushion, but socks are not able to protect a particular point or area where extra support or volume is needed. The socks provide the same amount of support everywhere. Moreover, most residual limbs shrink in size as the day progresses because walking and other activities drive blood and other fluid out of the residual limb, resulting in the need for additional layers of socks during the day. It is cumbersome to remove the socket, add or remove additional pairs of socks, and reattach the socket several times per day.
Thus, there is a need for an improved system that compensates for the volume fluctuations of the residual limb for improved performance and comfort of the prosthetic device.